Officially known as Kepler-16b, the planet is a gas giant similar in size to Saturn, orbiting at a distance of 105 million kilometres from its parent stars - similar to the distance Venus orbits the Sun.

However, both stars are smaller and cooler than the Sun, meaning the surface temperature of Kepler-16b is between -70°C and -100°C.

The planet, which is 200 light years from Earth, was detected using NASA's Kepler space telescope as it passed between Earth and its parent star, known as a transit. As the planet transits the star it reduces the amount of light received by the telescope. The amount, duration and frequency of this 'light dip' allows astronomers to determine the size of the planet and its distance from the star.

Calculating Kepler-16b's size and orbit proved to be slightly more difficult, due to the two stars transiting each, causing additional changes in brightness.

Long suspected

Dr Simon O'Toole, a research astronomer at the Australian Astronomical Observatory in Sydney is currently working on a project with amateur astronomer to detect planets orbiting binary stars using ground-based telescopes.

"We've had hints of this kind of thing before, but this is the first time you can say for sure it's a planet," says O'Toole who was not part of the study. "The other cases have been around very unusual binary stars, but these are stars much more like the Sun."

He says the concept of a planet with two suns, as depicted in the movie Star Wars is a popular motif of science fiction writers.

"It's sort of long been hoped for, but now we've got confirmation."

O'Toole says it could be possible other planets - including rocky Earth-like planets - are orbiting the stars, but they might be impossible to detect.

"The probability of all the objects lining up so that you can see these transits is quite low. If there are other rocky planets there we may not see them," he says.

O'Toole believes this latest discovery highlights the diverse range of solar systems in the universe.

"Our solar system is looking a bit unusual. But so is this, this is pretty unusual," he laughs. "The definition of a normal planetary system is becoming really hard to pin down. Just when we think we've got an idea, something comes along that surprises us."